The invention relates to a windshield wiper drive mechanism, having a pivotably supported drive shaft, a drive rocker solidly connected to it, a coupling rocker that is connected to the drive rocker by a drive joint, a support rocker that is connected to the coupling rocker by a support joint and is supported by a blind joint, a windshield wiper arm, which is connected to the coupling rocker by a joint, a contact-pressure spring that acts upon the windshield wiper arm relative to the coupling rocker, and a compensation joint that is disposed on one of the rockers.
One such windshield wiper drive mechanism is known from European Patent Disclosure EP-A 0 182 123. It serves to move a windshield wiper blade, secured to the windshield wiper arm, with a reciprocating motion over a windshield to be cleaned. To prevent twisting from occurring in the mechanism, based on a four-bar mechanism, that comprises the drive rocker, coupling rocker and support rocker, the compensation joint is provided, which is disposed on the coupling rocker and divides it into two portions movable relative to one another. This disadvantage in this construction is that the contact-pressure spring exerts a tilting moment on the coupling rocker, and this leads to increased stresses on the various bearings.
The object of the invention is thus to refine a windshield wiper drive mechanism of the type defined at the outset such that the tilting moment generated by the contact-pressure spring does not impair the operation of the windshield wiper drive mechanism.
The windshield wiper drive mechanism has the advantage that a compensation spring compensates entirely or at least in part for the tilting moment generated by the contact-pressure spring, so that the bearings of the coupling rocker experience less stress. Thus they can be made smaller, and non-jerking travel of the entire windshield wiper drive mechanism is obtained.